The goal of the proposed research by this new investigator and colleagues is to empirically derive operational definitions of bisexuality, and to explore patterns of demographic factors, mental health symptoms, health indicators, risk behaviors, and associated protective factors among bisexual adolescents as compared to their heterosexual or gay/lesbian peers. This will be accomplished through a series of secondary analyses replicated in ten large-scale adolescent surveys of health and risk behaviors, from the United States and Canada, each of which included items pertaining to sexual orientation. Across all the datasets, approximately 4 percent of students identified as bisexual or reported bisexual attractions or behaviors. Within each of the 10 adolescent health datasets, the following aims drive the research plan: AIM I: Empirically derive various operational definitions of bisexuality, based on self-identification, attraction, or behavior, and multidimensional models where possible within each dataset, in order to identify approaches to sexual orientation that can guide the subsequent analyses. As part of this process, describe patterns of demographic factors, including gender, age, family variables, ethnic and socioeconomic indicators, and community contexts, associated with bisexual adolescents as compared to gay/lesbian and to heterosexual adolescents. AIM II: Identify the association of bisexual orientation and behavior with health and risk behaviors in the areas of mental health, sexual health, substance use, safety, violence, and victimization, school performance, as compared to the associations among heterosexual and gay/lesbian respondents, with further examination of sub-samples grouped by gender, age, or ethnicity where feasible based on measurement and sample size considerations. AIM III: Identify protective factors associated with reduced prevalence of risk behaviors or with positive health indicators among bisexual adolescents in those domains identified in Aim II. AIM IV: Develop multivariate models of risk and protective factors relative to selected health indicators that differentiate bisexual adolescents from lesbian/gay and heterosexual adolescents. The replication of analyses within ten different data sets, across time and from different regions of North America, provides opportunities for establishing a base of knowledge about this population which can guide future research priorities and analytic strategies, health policy, and programmatic changes.